Heater and utilization system for converting small quantities of fusible solids



May 1, 1962 A. 1.. KRAFT 3,032,635 HEATER AND UTILIZATION SYSTEM FORCONVERTING SMALL QUANTITIES OF FUSIBLE SOLIDS Filed Oct. 5, 1960 FIG.Z

F/G. I

INVENTOR AUGUST L. KRAFT ATTORNEY United States Patent Ofiice 3,032,635Patented. May 1, 1962 3 032 635 HEATER AND UTILIZATlON SYSTEM FOR CON-VERTIN G SMALL QUANTITIES F FUSIBLE SOLIDS August L. Kraft, 120 BenderAve., Roselle Park, NJ. Filed Oct. 3, 1960, Ser. No. 60,080 4 Claims.(Cl. 219-19) This invention relates to a method and system for handlingin molten form materials which when cool are in the form of powderedsolids. In the case of materials such as the anhydrides, and solids suchas dichlorobenzidrine and dichlorohydrin, difficulties are encountered,due to the tendency of such materials to oxidize or sublime if held inthe molten state for any appreciable time.

It is accordingly an object of this invention to provide a systemincluding a fast acting heating agency which automatically will providea small, but fixed, supply of molten material.

An additional object of the invention is the provision of an eflicientand very fast acting heating unit.

A feature of the invention is a heating unit which may consist of asubstantially solid mass of conducting material which is sufficientlyporous to be permeable to liquids. A heating unit of this type provideslarge areas of heating surfaces, both internal and external, Which arein intimate contact with the material during the preliminary meltingstage and also during the passage of the molten material through theheater. Suitable solids for this purpose are carbon, fused quartz orsilica with controlled conducting impurities. If desired, porousstainless steel or porous bronze may be used.

In accordance with a further feature of the invention, the heating unitmay consist of a spirally wound ribbon of conducting material with theturns of the ribbons spaced by a corrugated ribbon of insulatingmaterial. In this form of the invention, the interstices created by thecorrugated spacer render the heater permeable to liquids.

Heaters constructed in accordance with this invention are capable ofoperation at very low wattage per unit area. The thickness or depth ofthe heater is a major factor in obtaining increased efliciency in termsof watts per unit area.

The invention will be better understood from the following detaileddescription, reference being had to the accompanying drawings.

FIG. 1 discloses apparatus and control circuits for converting fusiblesolids in powdered form into a liquid state together with an electricalcircuit for maintaining a small amount of molten material at a desiredlevel.

FIG. 2 discloses a heating unit in the form of a permeable conductor orsemi-conductor.

FIG. 3 illustrates a heating unit in which the heating unit is a discassembled by rolling into a spiral a ribbon of conducting material, theconvolutions of the spiral being spaced from one another by a continuouscorrugated strip which may be made of plastic or other insulatingmaterial. If desired, the convolutions may be wound so as to form arectilinear solid without departing from the spirit of my invention.

Referring now to FIG. 1, a container 1 of any desired configuration isprovided with a closure cap 2 and an outlet pipe 3 threaded into a boss4 formed on the bottom of the container. A heating unit 5 provided withsuitable connections to electrical conductors 6 and 7 is mounted in thelower portion of the container in any convenient manner. A float switchgenerally indicated at 8 is mounted below the heating unit with itsoperating float ball 9 at an elevation so disposed as to maintain themolten mate rial 10 at a desired level. A float operated switch 11 ismounted in pipe 3 and is so disposed as to operate when the level of themolten liquid from pipe 3 drops below a desired predetermined level. Apipe 12 is secured to pipe 3 by means of a threaded cap 13. Inoperation, the powder to be liquefied is inserted in receptacle 1 andrests on the upper surface of heater 5. Assuming that there is noliquefied material in the container below the heating unit, floatswitches 8 and 11 will both be closed. As a result, the closure ofswitch 15 completes an obvious circuit from a source of power 16 to theheating unit through switches 8 and 11 in series.

The heater, alternative forms of which will be more fully describedhereinafter, is of a nature to provide intense heat at relatively lowvoltages. As its entire upper surface is covered with the powder,liquefaction begins over the entire area simultaneously and with minimumdelay. The molten material, in response to both gravity and the pressureof the powder in the reservoir, will immediately start to enter theporous openings of the heater. During the passage of the molten materialthrough the heater, it is again in intimate contact with the walls ofthe interstices so that it is continuously heated throughout its passageand emerges from the bottom of the heater in drops which have attained ahigh temperature. After the lower pipes have filled and liquid 10 risesto the desired predetermined level, float valve 9 operates to open thecircuit of heater 5.

The molten material may then be dispensed as desired into utilizationequipment of any desired nature. When the liquid level in pipe 3 dropsbelow a predetermined level, float valve 11 closes. Float valve 9 willhave previously closed as soon as the level of liquid 10 starts to drop.As a result, the closure of switch 11 completes the circuit to heater 5and a new cycle is begun.

In FIG. 2 the heater is shown in the form of a solid block 26 providedwith suitable connecting electrodes as indicated at 17. Obviously theheater may be of any desired form, such as circular or elliptical discsor in rectilinear form of any desired proportions. Suitable materialsare carbon, fused quartz or silica with controlled conductingimpurities. Porous stainless steel and porous bronze of a compositioncommonly used as filters are satisfactory materials.

The heater shown in FIG. 3 is made by winding into spiral form aconducting strip 18 on which a corrugated strip 19 of insulatingmaterial formed of any suitable plastic has been superposed. Electricalconnection to the strip may be made at terminals 20 and 21. In this formof the invention the voids created by the successive alternations of thecorrugated strip provide the openings through which the liquefiedmaterial may pass. It is to be understood that the voids as shown inFIG. 3 are greatly magnified and that in practice they must be smallenough to prevent passage of the powdered solid. While the heater hasbeen shown in disc form, it may, if de sired, be Wound into any shapeappropriate to the cross section of the reservoir with which it is to beused.

It is evident that the conductor may be formed into a corrugated stripwith a flat strip of insulating material as the spacer.

What is claimed is:

1. An electrical heating unit consisting of a substantially solid cakeof conductive porous material, electrical terminals connected toseparated surfaces of said cake, a source of electrical energy,heat-liquefiable material in powder form, said cake being impervious tosaid material in powder form but permeable to said material afterliquefaction by said heating unit in response to the passage ofelectrical energy therethrough, the thickness of said cake beingsufficient to provide interstitial passages of substantial length sothat internal heat is applied to said liquefied material for anextensive period of time while in intimate contact with said passagesduring transit therethrough, whereby said liquefied material emerges athigh temperatures.

2. An electrical heating .unit consisting of a spirally wound strip offlat material, said strip being of substantial Width, the successiveconvolutions of said strip being spaced from one another by asubstantially continuous strip of corrugated material of like width, oneof said strips being an electrical conductor and the other strip beingan insulator, a source of electrical energy, electrical connections tothe conducting strip, heat liquefiable material in powderform, saidheating unit being impervious to said material in powder form butpermeable to said material after liquefaction by said heating unit inresponse to the passage of electrical energy therethrough,

the width of said strips being sufiicient to provide inter- .stitialpassa'ges of substantial length so that internal heat is applied to saidliquefied material for an extensive period of time while in intimatecontact with said passages during transit th'erethrough, whereby saidliquefied material emerges at high temperatures.

3. The combination of the heating unit of claim '1 with a utilizationsystem, said utilization system in'cluding'a container in which saidheater .is mounted, fusible material in the'form'of a powdered soliddisposed in said container and supported by said-heating unit,anelectrical circuit, rneanstto energize said heating unit by way ofsaid circuit and to liquefy said powdered material, a reservoir belowsaid heating unit, and automatically operated switches to maintain theliquefied material at a level between desired upper and lower limits.

4. The combination of the heating unit of claim 2 with a utilizationsystem, said utilization system including a container in which saidheater is mounted, fusible material in the form of a powdered soliddisposed in said container and supported by said heating unit, anelectrical circuit, means to energize said heating unit by way of saidcircuit and to liquefy said powdered material, a reservoir below saidheating unit, and automatically operated switches to maintain theliquefied material at a level between desired upper and lower'limits.

References Cited in the file of this patent UNITED STATES PATENTS m n i

